1. Field of the Invention
The present invention relates to a vertical or carousel-type conveyor assembly wherein the pallets are transported in a vertical orientation and are configured to accumulate along the conveyor at dedicated stop stations or during contact with other accumulated pallets.
2. Background Art
Prior art designs facilitate carrying of parts on a vertical pallet or carrier, but do not allow for accumulation of the pallets along an endless drive chain. These designs were indexing style conveyors, which relied upon the pallets being attached permanently to the drive chains on fixed centers. This type of design is greatly limited in flexibility in comparison to accumulating-type conveyors. An accumulating conveyor is one which allows pallets to stop moving with a continuously moving drive chain at dedicated stop stations, or while contacting other pallets. Accordingly, while the drive chain is continually driven, one or more pallets may be stopped and accumulated while the pallets are loaded or unloaded, or other operations are performed on the parts which are carried by the pallets, such as welding operations, etc.
Accumulating pallet assemblies are available, however these conveyors are of the over/under type, which carry the pallets in a horizontal position. One such conveyor assembly is described in U.S. Pat. No. 6,047,813, which is hereby incorporated in its entirety. This horizontal style conveyor is flexible in operation, but may become excessively wide if it must carry long or wide parts. This is undesirable because floor space is at a premium in manufacturing or assembly plants in which these conveyors are implemented.
Another shortcoming of horizontal-type conveyors is that products cannot be recirculated. The products must be removed prior to a terminal end of the conveyor so that the pallet may be transported, upside down, along the lower run back to a starting terminal end. Also, the over/under style conveyor requires that the pallets may only be stopped for loading and unloading between the terminal ends because special mechanical features are required at the terminal ends for transporting the pallets between the upper and lower runs, and therefore the terminal ends are generally enclosed and not accessible for stopping or not configurable for stopping. Also, the over/under style cannot carry parts around the terminal end from an upper level to a lower level without some mechanical means of holding the product on the fixture or tooling.
It is desirable to provide a much more flexible conveyor configuration capable of multiple load and unload positions while providing pallet accumulation and the ability to carry larger parts. It is also desirable to reduce the footprint of the conveyor equipment required to carry such parts.
Objects, features and advantages of the invention will become apparent upon reading of the following specification and claims, and are achieved by providing an endless chain arranged in a horizontal configuration and engaged with first and second sprockets which are rotatable about vertical axes of rotation. The endless chain is configured to transport a plurality of pallets along at least one rail by engagement with a clutch sprocket on each pallet. The clutch sprockets enable pallet accumulation anywhere along the length of the conveyor assembly. The vertical conveyor does not require that pallets be stopped for loading and unloading only between the terminal ends.
This xe2x80x9cverticalxe2x80x9d or xe2x80x9ccarouselxe2x80x9d type conveyor assembly will carry long or wide parts in a more upright position, therefore minimizing the overall footprint of the machine. Since the pallets travel in a continuously upright orientation, the attitude of the product being carried never changes. No other means of holding a part on the fixture or tooling is required during the entire travel of a complete revolution. Another benefit of the vertical design over an over/under style conveyor is the ability of the user to allow products to be recirculated if not removed prior to a terminal end.
The clutch sprockets on the carriers or pallets provide resistance to the chains by means of adjustable clutches and alignment bars. The adjustable clutches allow for adjustment of rolling resistance to accommodate the particular load requirements of the specific application for a particular machine. The sprockets are engaged on the inside of the multi-strand roller chain and the alignment bars are riding on the outside of the multi-strand roller chain.
A single driven sprocket located at the drive end of the conveyor drives the multi-strand roller chain. At the opposing end of the conveyor a similar sprocket acts as an idler and/or take-up sprocket to allow for proper tensioning of the multi-strand roller chain.
Unlike the horizontal-type accumulating pallet conveyor, the sprockets are mounted in such a way as to have the center shafts mounted vertically.
Each individual pallet or carrier is both supported and guided by a series of articulating xe2x80x9cVxe2x80x9d-grooved wheels assemblies which engage a mating xe2x80x9cVxe2x80x9d section machined track having a continuous path with straight runs and curved returns fitting together in a smooth and continuous path. This configuration is preferred to provide for a tight and more precise fit of the pallet or carrier relative to the track to maintain a tight tolerance. For some more forgiving applications, other guide wheel arrangements may be applied. The bottom of each pallet or carrier may have similar guides or simpler roller configurations depending on the particular application for a machine.